[Answered] How long did it take for oxygen to build up in the Earth's atmosphere to its present levels? A) ...

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Author Question: How long did it take for oxygen to build up in the Earth's atmosphere to its present levels? A) ... (Read 60 times)

809779

Hero Member
Posts: 579

on: Jul 27, 2018

How long did it take for oxygen to build up in the Earth's atmosphere to its present levels?

A) at least 542 million years
B) at least 360 million years
C) at least 2 billion years
D) at least 3.5 billion years

Question 2

Express the following number to three significant figures: 21.25 m

What will be an ideal response?

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Marked as best answer by a Subject Expert

blakeserpa

Sr. Member
Posts: 338

Reply #1 on: Jul 27, 2018

Answer to Question 1

C

Answer to Question 2

21.3 m

809779

Member
Posts: 579

Reply 2 on: Jul 27, 2018

Wow, this really help

Jossy

Member
Posts: 336

Reply 3 on: Yesterday

Excellent

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